4 files changed, 5 insertions, 35 deletions
diff --git a/apps/dav/lib/CalDAV/Activity/Provider/Base.php b/apps/dav/lib/CalDAV/Activity/Provider/Base.php
index 48ed7b8b107..672129a8311 100644
--- a/apps/dav/lib/CalDAV/Activity/Provider/Base.php
+++ b/apps/dav/lib/CalDAV/Activity/Provider/Base.php
@@ -38,9 +38,6 @@ abstract class Base implements IProvider {
 	/** @var IUserManager */
 	protected $userManager;
 
-	/** @var string[]  */
-	protected $userDisplayNames = [];
-
 	/** @var IGroupManager */
 	protected $groupManager;
 
diff --git a/apps/dav/lib/CalDAV/CalDavBackend.php b/apps/dav/lib/CalDAV/CalDavBackend.php
index b00a4f9d6ed..a894b65d756 100644
--- a/apps/dav/lib/CalDAV/CalDavBackend.php
+++ b/apps/dav/lib/CalDAV/CalDavBackend.php
@@ -417,7 +417,7 @@ class CalDavBackend extends AbstractBackend implements SyncSupport, Subscription
 
 			[, $name] = Uri\split($row['principaluri']);
 			$uri = $row['uri'] . '_shared_by_' . $name;
-			$row['displayname'] = $row['displayname'] . ' (' . $this->getUserDisplayName($name) . ')';
+			$row['displayname'] = $row['displayname'] . ' (' . ($this->userManager->getDisplayName($name) ?? ($name ?? '')) . ')';
 			$components = [];
 			if ($row['components']) {
 				$components = explode(',',$row['components']);
@@ -493,25 +493,6 @@ class CalDavBackend extends AbstractBackend implements SyncSupport, Subscription
 		return array_values($calendars);
 	}
 
-
-	/**
-	 * @param $uid
-	 * @return string
-	 */
-	private function getUserDisplayName($uid) {
-		if (!isset($this->userDisplayNames[$uid])) {
-			$user = $this->userManager->get($uid);
-
-			if ($user instanceof IUser) {
-				$this->userDisplayNames[$uid] = $user->getDisplayName();
-			} else {
-				$this->userDisplayNames[$uid] = $uid;
-			}
-		}
-
-		return $this->userDisplayNames[$uid];
-	}
-
 	/**
 	 * @return array
 	 */
diff --git a/apps/dav/lib/CalDAV/Schedule/IMipPlugin.php b/apps/dav/lib/CalDAV/Schedule/IMipPlugin.php
index 2c7b06a4396..91610682ef2 100644
--- a/apps/dav/lib/CalDAV/Schedule/IMipPlugin.php
+++ b/apps/dav/lib/CalDAV/Schedule/IMipPlugin.php
@@ -178,12 +178,7 @@ class IMipPlugin extends SabreIMipPlugin {
 		$recipientName = $iTipMessage->recipientName ?: null;
 
 		if ($senderName === null || empty(trim($senderName))) {
-			$user = $this->userManager->get($this->userId);
-			if ($user) {
-				// getDisplayName automatically uses the uid
-				// if no display-name is set
-				$senderName = $user->getDisplayName();
-			}
+			$sender = $this->userManager->getDisplayName($this->userId) ?? $this->userId;
 		}
 
 		/** @var VEvent $vevent */
@@ -225,7 +220,7 @@ class IMipPlugin extends SabreIMipPlugin {
 		];
 
 		$fromEMail = Util::getDefaultEmailAddress('invitations-noreply');
-		$fromName = $l10n->t('%1$s via %2$s', [$senderName, $this->defaults->getName()]);
+		$fromName = $l10n->t('%1$s via %2$s', [$senderName ?? $this->userId, $this->defaults->getName()]);
 
 		$message = $this->mailer->createMessage()
 			->setFrom([$fromEMail => $fromName])
diff --git a/apps/dav/tests/unit/CalDAV/Schedule/IMipPluginTest.php b/apps/dav/tests/unit/CalDAV/Schedule/IMipPluginTest.php
index 0d8076f7aa4..0b64704a87e 100644
--- a/apps/dav/tests/unit/CalDAV/Schedule/IMipPluginTest.php
+++ b/apps/dav/tests/unit/CalDAV/Schedule/IMipPluginTest.php
@@ -183,13 +183,10 @@ class IMipPluginTest extends TestCase {
 		$message = $this->_testMessage();
 		$message->senderName = null;
 
-		$user = $this->createMock(IUser::class);
-		$user->method('getDisplayName')->willReturn('Mr. Wizard');
-
 		$this->userManager->expects($this->once())
-			->method('get')
+			->method('getDisplayName')
 			->with('user123')
-			->willReturn($user);
+			->willReturn('Mr. Wizard');
 
 		$this->_expectSend();
 		$this->plugin->schedule($message);